An expansion valve comprising a diaphragm and at least two outlet openings

ABSTRACT

An expansion valve ( 1 ) comprising an inlet opening and at least two outlet openings ( 5 ) is disclosed. The inlet opening is adapted to receive fluid medium in a liquid state, and the outlet openings ( 5 ) are adapted to deliver fluid medium in an at least partly gaseous state. The expansion valve ( 1 ) further comprises a diaphragm ( 6 ), and at least two valve seats ( 4 ), each valve seat ( 4 ) being fluidly connected to one of the outlet openings ( 5 ). Each of the valve seats ( 4 ) forms a valve in combination with the diaphragm ( 6 ), the position of the diaphragm ( 6 ) thereby simultaneously defining an opening degree of each of the valves. A well defined distribution of fluid flow towards each of the outlet openings ( 5 ) is easily defined by movements of the diaphragm ( 6 ). The distribution takes place before or during expansion of the fluid medium. The expansion valve ( 1 ) may be arranged in an refrigerant path of a refrigeration system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of and incorporates byreference essential subject matter disclosed in International PatentApplication No. PCT/DK2009/000242 filed on Nov. 19, 2009 and DanishPatent Application No. PA 2008 01630 filed Nov. 20, 2008.

FIELD OF THE INVENTION

The present invention relates to an expansion valve, in particular foruse in a refrigeration system, e.g. an air condition system. Theexpansion valve of the present invention is adapted to distribute fluidmedium to at least two parallel flow paths, e.g. in the form of at leasttwo parallel evaporators or evaporator tubes.

BACKGROUND OF THE INVENTION

In a fluid circuit, such as a refrigerant circuit of a refrigerationsystem, it is sometimes desirable to split the flow path into two ormore parallel flow paths along part of the fluid circuit. This is, e.g.,the case in refrigeration systems comprising two or more evaporatorsarranged in parallel. It may further be desirable to be able to controlthe fluid flow to each of the parallel flow paths, e.g. in such a mannerthat a substantially equal fluid distribution is obtained, or in such amanner that the system is operated in an optimum manner, e.g. in termsof energy consumption or efficiency.

In some previous attempts to control distribution of refrigerant betweentwo or more parallel flow paths in a refrigeration system, a distributoris arranged downstream relative to an expansion valve in the refrigerantflow path. Thus, the refrigerant is distributed after expansion of therefrigerant, i.e. the refrigerant is mainly gaseous. This has thedisadvantage that it is very difficult to control the flow ofrefrigerant to obtain a substantially equal distribution between theparallel flow paths.

SUMMARY OF THE INVENTION

It is an object of embodiments of the invention to provide an expansionvalve which is capable of controlling distribution of fluid to two ormore parallel flow paths.

It is a further object of embodiments of the invention to provide anexpansion valve which is adapted to manage distribution of fluid to twoor more parallel flow paths in an easy manner.

In a first aspect the present invention provides an expansion valvecomprising:

-   -   an inlet opening adapted to receive fluid medium in a liquid        state,    -   at least two outlet openings, each being adapted to deliver        fluid medium in an at least partly gaseous state,    -   a diaphragm, and    -   at least two valve seats, each valve seat being fluidly        connected to one of the outlet openings, and each of the valve        seats forming a valve in combination with the diaphragm, the        position of the diaphragm thereby simultaneously defining an        opening degree of each of the valves.

The expansion valve of the invention defines flow paths between theinlet opening and the at least two outlet openings. Fluid medium in aliquid state is received at the inlet opening and fluid medium in an atleast partly gaseous state is delivered at the outlet openings. In thepresent context the term ‘liquid state’ should be interpreted to meanthat the fluid medium entering the expansion valve via the inlet openingis substantially in a liquid phase. Similarly, in the present contextthe term ‘at least partly gaseous state’ should be interpreted to meanthat the fluid medium leaving the expansion valve via the outletopenings is completely in a gaseous phase, or at least a part, e.g. asubstantial part, of the volume of the fluid medium leaving theexpansion valve is in a gaseous phase. Accordingly, at least a part ofthe fluid medium entering the expansion valve undergoes a phasetransition from the liquid phase to the gaseous phase when passingthrough the expansion valve.

The inlet opening and the outlet openings may preferably be fluidlyconnected to one or more other components, such as other components of arefrigeration system. The expansion valve may advantageously form partof a flow system, such as a flow circuit.

The expansion valve further comprises a diaphragm and at least two valveseats. Each of the valve seats is fluidly connected to one of the outletopenings. The diaphragm and the valve seats are arranged relative toeach other in such a manner that each of the valve seats forms a valvein combination with the diaphragm. Since each of the valve seats isfluidly connected with one of the outlet openings, the valves formed bythe valve seats and the diaphragm define fluid flow towards each of theoutlet openings.

It should be noted that the valves could be formed by the valve seatsand specific parts or regions of the diaphragm, e.g. in the form ofvalve cones or valve plates mounted on the diaphragm.

Accordingly, when the diaphragm is moved it simultaneously performsrelative movements with respect to each of the valve seats, and therebysimultaneously changing the opening degrees of each of the valves formedby the valve seats and the diaphragm. Thus, the opening degrees areadjusted synchronously, thereby at least substantially maintaining adistribution key among the outlet openings. Furthermore, this is a verysimple manner of simultaneously controlling fluid flow towards at leasttwo outlet openings. Finally, the distribution of fluid medium amongparallel flow paths takes place before or during expansion of the fluidmedium, because the distribution takes place in the expansion valve.This makes it easier to accurately control the fluid distribution.

The expansion valve may further comprise a thermostatic element and adiaphragm moving element arranged to operatively interconnect thethermostatic element and the diaphragm, movements of the diaphragmthereby being caused by the thermostatic element. According to thisembodiment, the thermostatic element determines the position of thediaphragm, and thereby the thermostatic element determines the openingdegrees of each of the valves defined by the valve seats and thediaphragm. The diaphragm moving element may be arranged in directabutment with the diaphragm. In this case movements of the diaphragmmoving element in response to a pressure change of the thermostaticelement will directly cause corresponding movements of the diaphragm.The diaphragm moving element may, e.g., be a block arranged in abutmentwith the diaphragm and connected to the thermostatic element, e.g. via arod or a piston. The diaphragm moving element may, thus, be or comprisea piston.

As an alternative, the diaphragm may be moved in any other suitablemanner, e.g. using an actuator, such as an electrical or a hydraulicactuator.

The expansion valve may further comprise means for biasing the diaphragmin a direction away from the valve seats. According to this embodiment,the diaphragm is forced towards a position defining a maximum openingdegree for the valves defined by the valve seats and the diaphragm. Whenit is desired to decrease the opening degrees of the valves, work mustbe performed against the biasing force.

Alternatively, the expansion valve may further comprise means forbiasing the diaphragm in a direction towards the valve seats. Accordingto this embodiment, the diaphragm is forced towards a position defininga minimum opening degree for the valves defined by the valve seats andthe diaphragm, i.e. towards a closed position. When it is desired toincrease the opening degree, work must be performed against the biasingforce.

In any of the embodiments described above, the biasing means may, e.g.,comprise one or more springs, such as compressible springs.

The diaphragm may be provided with at least one through-going hole. Thisallows the diaphragm to be very flexible without requiring that thediaphragm is very thin. It is easier to manufacture the diaphragm with acertain thickness and subsequently provide a desired flexibility byproviding one or more through-going holes in the diaphragm, than todirectly manufacture a thin diaphragm having the desired flexibility. Aflexible diaphragm ensures that the diaphragm can be moved accuratelyand swiftly to provide an accurate and prompt change in opening degreeof the valves defined by the valve seats and the diaphragm.

Alternatively or additionally, the diaphragm may be provided with atleast two valve seat engaging regions, each valve seat engaging regionbeing arranged adjacent to a valve seat in such a manner that the valveseats and the valve seat engaging regions pair wise define the at leasttwo valves. The valve seat engaging regions may, e.g. be parts of thediaphragm which define a level which is different from a level definedby the rest of the diaphragm. Such parts may, e.g., be in the form of‘hills’ or ‘valleys’ formed on the diaphragm. The valve seat engagingregions may advantageously be arranged closer to the valve seats thanthe rest of the diaphragm. Thereby it can be ensured that the valvesdefined by the valve seats and the valve seat engaging regions can beclosed tightly. Alternatively or additionally, the valve seat engagingregions may be or comprise valve cones or valve plates mounted on thediaphragm.

According to a second aspect the invention provides a refrigerationsystem comprising:

-   -   at least one compressor,    -   at least one condenser,    -   at least two evaporators arranged in parallel along a        refrigerant flow path of the refrigeration system, and    -   an expansion valve according to the first aspect of the        invention, said expansion valve being arranged in such a manner        that each of the at least two outlet openings is arranged to        deliver refrigerant to one of the evaporators.

Thus, the expansion valve according to the first aspect of the inventionmay advantageously be arranged in a refrigeration path of arefrigeration system, e.g. a refrigeration system used in a coolingarrangement or an air condition system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings in which

FIG. 1 is a cross sectional view of an expansion valve according to anembodiment of the invention,

FIG. 2 shows a first diaphragm for use in an expansion valve accordingto an embodiment of the invention,

FIG. 3 shows a second diaphragm for use in an expansion valve accordingto an embodiment of the invention, and

FIG. 4 shows a third diaphragm for use in an expansion valve accordingto an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a cross sectional view of an expansion valve 1 according to anembodiment of the invention. The expansion valve 1 comprises a firstvalve part 2 and a second valve part 3. The first valve part 2 has anumber of valve seats 4, two of which are visible, arranged therein.Each of the valve seats 4 is fluidly connected to an outlet opening 5.

The expansion valve 1 further comprises a diaphragm 6 arranged adjacentto the first valve part 2 in such a manner that it covers the valveseats 4. Thereby movements of the diaphragm 6 relatively to the valveseats 4 define the size of a fluid passage through the valve seats 4 andtowards the outlet openings 5. Thereby a number of valves are defined bythe valve seats 4 and the diaphragm 6, and the opening degrees of thevalves are determined by the position of the diaphragm 6 relative to thevalve seats 4. A compressible spring 7 is arranged to push the diaphragm6 in a direction towards the valve seats 4, i.e. towards a positiondefining a minimum opening degree for the valves defined by the valveseats 4 and the diaphragm 6.

The diaphragm 6 is operatively connected to a thermostatic element (notshown) via a piston 8. The thermostatic element controls movements ofthe piston 8 as indicated by arrow 9, thereby controlling movement ofthe diaphragm 6. When the piston 8 is moved in a downwards direction,i.e. in a direction towards the position of the diaphragm 6, thediaphragm 6 is pushed in a direction away from the valve seats 4.Thereby the size of passages defined between the diaphragm 6 and each ofthe valve seats 4 is increased, thereby increasing the opening degreesof the valves defined by the valve seats 4 and the diaphragm 6. When thepiston 8 is moved in the opposite direction, the diaphragm 6 is moved ina direction towards the valve seats 4 by the spring 7, i.e. the openingdegrees of the valves defined by the valve seats 4 and the diaphragm 6are decreased.

The expansion valve 1 of FIG. 1 may be operated in the following manner.Fluid medium in a substantially liquid state is received in theexpansion valve 1 via an inlet opening (not shown) arranged in an upperpart of the piston 8. The fluid medium is led through the piston 8towards the diaphragm 6 and further towards the valve seats 4. Dependingon the position of the diaphragm 6, and thereby the opening degrees ofthe valves defined by the valve seats 4 and the diaphragm 6, the fluidis led through the valve seats 4 and leaves the expansion valve 1 viathe outlet openings 5. During this the fluid medium is expanded, and thefluid medium leaving the expansion valve 1 via the outlet openings 5 istherefore in an at least partly gaseous state.

FIG. 2 shows a diaphragm 6 which is suitable for use in the expansionvalve 1 of FIG. 1. The diaphragm 6 is provided with four through-goingholes 10. When the diaphragm 6 is mounted in an expansion valve 1 it ispositioned in such a manner that the through-going holes 10 are notarranged at positions corresponding to valve seats 4. Thereby thediaphragm 6 is capable of providing a required sealing effect towardsthe valve seats 4.

Since the diaphragm 6 is provided with through-going holes 10 it is moreflexible than a diaphragm having the same thickness, but without thethrough-going holes 10. The increased flexibility allows the diaphragm 6to react fast to movements of the piston 8 in response to changes in thethermostatic element. Thereby the response time of the valve is reduced.Furthermore, a more accurate positioning of the diaphragm 6 can beobtained, and thereby it is possible to adjust the opening degrees ofthe valves defined by the valve seats 4 and the diaphragm 6 moreaccurately.

FIG. 3 shows an alternative diaphragm 6 which is suitable for use in theexpansion valve 1 of FIG. 1. In the lower part of FIG. 3 the diaphragm 6is seen from above, and in the upper part of FIG. 3 the diaphragm 6 isshown in a cross sectional view.

The diaphragm 6 of FIG. 3 is provided with four elevated regions 11.When the diaphragm 6 is mounted in an expansion valve 1 it is positionedin such a manner that the elevated regions 11 are arranged at positionscorresponding to the positions of the valve seats 4, and in such amanner that the elevated regions 11 are arranged closer to the firstvalve part 2 than the remaining part of the diaphragm 6. Thereby it canbe ensured that a substantially fluid tight fit is provided between thediaphragm 6 and the valve seats 4 when the diaphragm 6 is in theposition defining a minimum opening degree of the valves.

FIG. 4 shows yet an alternative diaphragm 6 which is suitable for use inthe expansion valve 1 of FIG. 1. The diaphragm 6 of FIG. 4 is verysimilar to the diaphragm 6 of FIG. 3, since the diaphragm 6 of FIG. 4 isalso provided with elevated regions 11. However, the elevated regions 11of FIG. 4 are shaped in a slightly different manner.

While the present invention has been illustrated and described withrespect to a particular embodiment thereof, it should be appreciated bythose of ordinary skill in the art that various modifications to thisinvention may be made without departing from the spirit and scope of thepresent.

1. An expansion valve comprising: an inlet opening adapted to receivefluid medium in a liquid state, at least two outlet openings, each beingadapted to deliver fluid medium in an at least partly gaseous state, adiaphragm, and at least two valve seats, each valve seat being fluidlyconnected to one of the outlet openings, and each of the valve seatsforming a valve in combination with the diaphragm, the position of thediaphragm thereby simultaneously defining an opening degree of each ofthe valves.
 2. The expansion valve according to claim 1, furthercomprising a thermostatic element and a diaphragm moving elementarranged to operatively interconnect the thermostatic element and thediaphragm, movements of the diaphragm thereby being caused by thethermostatic element.
 3. The expansion valve according to claim 2,wherein the diaphragm moving element is arranged in direct abutment withthe diaphragm.
 4. The expansion valve according to claim 2, wherein thediaphragm moving element is or comprises a piston.
 5. The expansionvalve according to claim 1, further comprising means for biasing thediaphragm in a direction away from the valve seats.
 6. The expansionvalve according to claim 1, further comprising means for biasing thediaphragm in a direction towards the valve seats.
 7. The expansion valveaccording to claim 1, wherein the diaphragm is provided with at leastone through-going hole.
 8. The expansion valve according to claim 1,wherein the diaphragm is provided with at least two valve seat engagingregions, each valve seat engaging region being arranged adjacent to avalve seat in such a manner that the valve seats and the valve seatengaging regions pair wise define the at least two valves.
 9. Arefrigeration system comprising: at least one compressor, at least onecondenser, at least two evaporators arranged in parallel along arefrigerant flow path of the refrigeration system, and an expansionvalve according to claim 1, said expansion valve being arranged in sucha manner that each of the at least two outlet openings is arranged todeliver refrigerant to one of the evaporators.